Method and apparatus for use with compensating tubing anchor



Jan. 5, 1965 M. B. CONRAD 3,164,094

METHOD AND APPARATUS FOR USE WITH COMPENSATING TUBING ANCHOR Filed Feb. 1, 1963 IZ-3[ MARTIN B. CONRAD INVENTOR.

ATTORNEYS.

United States Patent 3,164,094 METHOD AND APPARATUS FUR UE WITH COMPENSATING TUBING ANCHOR Martin B. Conrad, R0. Box 1026, Downey, Calif.

Filed Feb. 1, 1963, Ser. No. 255,534

Claims. (Cl. 1031) This invention relates to the pumping of oil wells and is particularly directed to an improved method and apparatus for temporarily imposing a back pressure on gas containing well fluid being pumped through the eduction conduit, after the tubing string has been withdrawn and reinstalled in the well to service the pump. The purpose of imposing the back pressure temporarily is to load the pump during the return stroke and thereby stretch the tubing string. The compensating tubing anchor then maintains the tubing string in stretched position and prevents reciprocating movement of the tubing within the well during the action of the reciprocating pump.

As pointed out in my prior Patents Nos. 3,011,557 and 3,011,558, showing hydraulically operated compensating tubing anchor devices, it is desirable to anchor the lower portion of the tubing string against reciprocating movement in order to prevent wear between the tubing and the casing. Mechanically operated compensating tubing devices may also be employed for the same purpose. It is important to minimize variations in the forces applied by the compensating tubing anchor device through its wedge slips to the casing, to eliminate the tendency of the slips to cut through the casing.

In accordance with the present invention, methods and apparatus are provided for temporarily imposing a back pressure on the gas containing well fluid being pumped through the tubing, the back pressure serving to load the pump on the return stroke to stretch the tubing string, and the compensating tubing anchor device then acting to maintain the tubing string in stretched position. This back pressure is imposed by means of a device at the surface which serves temporarily to restrict flow of the pumped well fluid until such time as all or a portion of the flow-restricting device is dissipated by action of the pumped well fluid. The word dissipated as used herein is intended to cover dissolving, disintegrating, or eroding or otherwise gradual wearing away of material by action of the pumped well fluid.

In the drawings:

FIGURE 1 is a schematic diagram showing a well pumping apparatus and showing the method and a pre ferred apparatus for carrying out this invention;

FIGURE 2 is a longitudinal sectional view of a portion of the device shown in FIGURE 1;

FIGURE 3 is a transverse sectional view taken substantially on lines 3-3 as shown in FIGURE 2; and

FIGURE 4 is a sectional view showing a modification.

Referring to the drawings, the power-driven pumping jack 1t) reciprocates a string of sucker rods 11 connected to the pump 12, to raise well fluid through the eduction tube or tubing string 13. The well fluid, thus pumped, passes through the well head 14 and out through a flow conduit generally designated 15. A compensating tubing anchor shown diagrammatically at 16 connects the lower portion of the tubing string 13 to the well casing 17. This tubing anchor 16 may be of the hydraulically operated construction shown in either of my prior Patents Nos. 3,011,557 or 3,011,558, or may be of conventional mechanically operated type. The purpose of the anchor device is to prevent vertical or reciprocating movement of the lower end of the tubing string 13 under the varying load imposed on the tubing string by the reciprocating sucker rods 11 and pump 12.

In accordance with the present invention, a method and ice apparatus are employed for temporarily imposing a back pressure on the fluid pumped through the tubing string 13, such back pressure acting to load the pump and cause the compensating tubing anchor 16 to anchor the tubing string 13 in stretched position. The method may be car ried out with either the apparatus of FIGURE 2 or FIG- URE 4. Referring to FIGURE 2, the flow pipe 15a and the tubular member 1512 form a part of the flow conduit generally designated 15. The member 15b includes a stationary shell 18, which receives a cylindrical flowrestricting element 19. The element 19 is clamped against the stationary shoulder 20 by means of the nut 21. A small hole or orifice 22 extends through the element 19. The member 15!) also includes a housing 23 encircling the shell 18. This housing is connected by threads 24 to the terminal sleeve 25.

A tubular valve 26 is mounted to slide axially within the bore 27 of the terminal sleeve 25, and this valve has an end face 23 adapted to contact the seat 2? and to form a seal. The seat 29 is provided on one end of the nut 21. A spring 30 is bottomed on the shoulder 31 and acts against the tubular valve 26 to hold the valve face 28 in sealing engagement with the valve seat 29. An O-ring 32 is provided to prevent leakage between the tubular valve 26 and the bore 27.

Ports 33 and the shell 18 upstream from the flowrestricting element 1? communicate with the annular space 34 between the shell 18 and the housing 23. Accordingly, well fluid entering the sleeve 18 passes through the ports 33 and into the annular space 34 and acts against the exposed area of the tubular valve 26, opposing the action of the spring 30. When the pressure reaches a predetermined magnitude, the tubular valve 26 moves axially in a direction to compress the spring 30, thereby ermitting flow of well fluid from the annular space 34 into the interior 35 of the tubular valve 26 and out through the central opening 36 in the stationary part 25. From this description it will be understood that a bypass is provided around the flow-restricting element 19 which opens when the unit pressure of the pumped well fluid builds up to a predetermined magnitude.

Pumped well fluid under pressure flows through the bypass, and it also flows through the small orifice 22. The material of the element 19 containing the orifice 22 is gradually dissolved or eroded by well fluid passing through the orifice 22, and the central opening gradually enlarges until substantially no back pressure is imposed. By that time the valve 26 has closed and remains closed.

Means are provided to cushion the back pressure imposed on the well fluid being pumped and as shown in the drawings this means includes the air cushion chamber 40 connected to the upper portion of the housing 23 by means of the threaded neck 41. A quantity of air or other gas is trapped in the upper portion of the air cushion member 411, and the volume of this air changes cyclically in accordance with pressure changes of the well fluid in the annular space 34 during each cycle of the pump.

In the modification shown in FIGURE 4, the flowrestricting element 1% is provided with a central opening or orifice 22a, through which the entire volume of pumped well fluid must pass. The material of the element 19a is the same as that of the element 19, described above, and is such that passage of well fluid therethrough causes the material to dissolve, erode, disintegrate, or otherwise be dissipated in a short time, for example, a day or two. After that time, the proportion of gas in the well fluid, that is not normal to regular pumping action, will have been dispelled from the well. After that equi librium conditions will have been reached, and the tubing anchor will have been forced below its no-load position for equilibrium well conditions.

areaaa Among materials which are suitable for the flowrestricting element 19 are gypsum, gypsum anhydrite, or glanberite. These materials are given by way of illustration only, and other suitable materials may be used, if desired.

Having fully described my invention, it is to be understood that I am not to be limited to the details herein set forth, but that my invention is of the full scope of the appended claims.

I claim:

1. For use with an oil well pump installation having a tubing string extending into a well casing from a well head and having a reciprocating pump connected to the tubing string, and'having a compensating anchor device operable to prevent upward movement of the tubing string relative to the well casing during operation of the pump, the well head having a flow conduit leading from the tubing string, the improvement comprising: a hollow member, means for removably connecting said hollow member to the flow conduit to receive the full flow of gas-containing well fluid discharged from the tubing string through the well head, means including a flow-restricting element mounted in said hollow member to impose a back pressure on pumped fluid in the tubing string and thereby cause the anchor device to tension the tubing string, said element being formed of material adapted to be slowly dissipated by the well fluid, whereby free flow is thereafter permitted through said hollow member in the absence of said element.

2. For use with an oil well pump installation having a tubing string extending into a well casing from a Well head and having a reciprocating pump connected to the tubing string, and having a compensating anchor device operable to prevent upward movement of the tubing string relative to the well casing during operation of the pump, the well head having a flow conduit leading from the tubing string, the improvement comprising, in combination: a hollow member, means for removably connecting said hollow member to the flow conduit to receive the fulltflow of gas-containing well fluid discharged from the tubing string through the well head, a flow-restricting element mounted in said hollow member to impose a back pressure on pumped fluid in the tubing string and thereby cause the anchor device to tension the tubing string,

said element being formed of material adapted to be slowly dissipated by the well fluid, whereby free flow is permitted through said hollow member in the absence of said element, means on said member forming a bypass passage around said element, valve means adapted to restrict flow through said bypass passage, and bias means acting in a direction to close said valve means.

3. The combination of claim 2 in which an air chamber member is attached to said hollow member in communication with said bypass passage.

4. For use with an oil well pump installation having a tubing string extending into a Well casing from a well head and having a reciprocating pump connected to the tubing string, and having a compensating anchor device operable to prevent upward movement of the tubing string relative to the well casing during operation of the pump, the well head having a flow conduit leading from the tubing string, the improvement comprising: a flowrestricting bean element mounted in the path of gascontaining well fluid discharged from the tubing string through the well head, said bean element acting to impose a back pressure on pumped fluid in the tubing string and thereby cause the anchor device to tension the tubing string, said bean element being formed of material adapted to be slowly dissipated by the Well fluid, whereby free flow is permitted through the flow conduit in the absence of said bean element.

5. The method of temporarily imposing a back pressure on gas-containing well fluid being produced from a pumping oil well having a reciprocating pump in a well tubing operated by sucker rods, and having a flow conduit at the surface connected to the tubing, comprising placing a flow-restricting bean element in the flow conduit leading from the well, the bean element being formed of material adapted to be slowly dissipated by the well fluid so that normal free flow of well fluid is reestablished after the bean element has disappeared.

References Cited by the Examiner UNITED STATES PATENTS 2,319,514 5/43 Penfield l66224 2,330,564 9/43 Dyer 166-224 2,332,749 10/43 Page 166-2l2 2,735,497 2/56 Erumleu l662l2 3,001,557 12/61 Conrad 166-212 LAURENCE V. EFNER, Primary Examiner. 

1. FOR USE WITH AN OIL WELL PUMP INSTALLATION HAVING A TUBING STRING EXTENDING INTO A WELL CASING FROM A WELL HEAD AND HAVING A RECIPROCATING PUMP CONNECTED TO THE TUBING STRING, AND HAVING A COMPENSATING ANCHOR DEVICE OPERABLE TO PREVENT UPWARD MOVEMENT OF THE TUBING STRING RELATIVE TO THE WELL CASING DURING OPERATION OF THE PUMP, THE WELL HEAD HAVING A FLOW CONDUIT LEADING FROM THE TUBING STRING, THE IMPROVEMENT COMPRISING: A HOLLOW MEMBER, MEANS FOR REMOVABLY CONNECTING SAID HOLLOW MEMBER TO THE FLOW CONDUIT TO RECEIVE THE FULL OF GAS-CONTAINING WELL FLUID DISCHARGED FROM THE TUBING STRING THROUGH THE WELL HEAD, MEANS INCLUDING A FLOW-RESTRICTING ELEMENT MOUNTED IN SAID HOLLOW MEMBER TO IMPOSE A BACK PRESSURE ON PUMPED FLUID IN THE TUBING STRING AND THEREBY CAUSE THE ANCHOR DEVICE TO TENSION THE TUBING STRING, SAID ELEMENT BEING FORMED OF MATERIAL ADAPTED TO BE SLOWLY DISSIPATED BY THE WELL FLUID, WHEREBY FREE FLOW IS THEREAFTER PERMITTED THROUGH SAID HOLLOW MEMBER IN THE ABSENCE OF SAID ELEMENT. 